1. Field of the Invention
The present invention generally relates to a sales data processing method and a sales data processing system, suitable for an electronic cash register and a POS (Point-of-Sales) system. More specifically, the present invention is directed to a sales data processing method and a sales data processing system, capable of automatically calculating sales taxes with respect to sales amounts of taxable merchandise by referring to a tax table.
2. Description of the Related Art
Nowadays, the U.S. tax system is a rather complicated system. Therefore, very heavy workloads for executing tax processes are given to relatively small retail shops. For instance, state sales tax normally belongs to direct tax paid by buyers. This state sales tax is paid as state tax in response to sales amounts in retail shops. In a general retail shop, tax amounts listed in a tax amount table (tax chart) published by each state are manually set into a tax table stored in an electronic cash register in combination with sales amount ranges. This electronic cash register is installed in this retail shop in order to calculate this state sales tax. Then, tax amounts depending on sales amounts are calculated with reference to this tax amount table set in the electronic cash register.
However, this registering/setting work is very heavy, because the tax chart is voluminous, as indicated in FIG. 21, and because the tax amounts are subdivided in accordance with the respective sales ranges. Under these circumstances, all pages of the tax chart are not manually set/registered into the tax table. Instead the setting/registering work is performed by utilizing the regularity of each price range corresponding to the sales tax.
Concretely speaking, an operator first calculates difference values one by one in a manual manner with reference to the tax chart shown in FIG. 21 (also see COLORADO SALES TAX CHART). One difference value is calculated by subtracting one preceding "TO"-value (namely, a high end maximum break point) from one "TO"-value of each of the price ranges, corresponding to a tax amount. Then, the operator writes these manually calculated difference values on paper. Thereafter, the operator discriminates the non-cyclic patterns (e.g., "10" and "14" in FIG. 21) having regularity from the cyclic patterns (e.g., "17, 17, 16, 17, 17, 16" in FIG. 21) in the difference value series of the "TO" values. Finally, the operator manipulates the key input device to enter the difference values of the non-cyclic patterns and the difference values of one pattern series into the tax table of the electronic cash register.
As previously described, when the tax table is set, the above-explained various manual operators carried out by the operator may contain many careless mistakes and these operators are also cumbersome to perform. Moreover, since this sort of tax chart is frequently changed, the tax table setting operators must be frequently carried out, which may forcibly require very heavy workloads to the operator.